1. Field of the Invention
The present invention relates to improvements in fluid flow control valves, and more particularly but not by way of limitation, the invention relates to self sealing valves.
2. Discussion of the Prior Art
U.S. Pat. No. 3,815,869, issued to Smith, presents a means of sealing a flow passageway in the event that the sealing member is destroyed, a feature also present in U.S. Pat. No. 3,642,247, issued to Scaramucci, the present Applicant. The Smith patent teaches the limited displacement of a butterfly disc under fluid pressure to close the flow passageway if the seal member is destroyed. However, the circumstances that would destroy the seal member would also cause the packer about the disc shaft to be destroyed, and the Scaramucci valve effects the same fire safe result.
Neither of the above patents mentions the intended problem of fluid leakage from the operating stem aperture in the event the valve seals and packers are destroyed. This means that fluid would still escape the confines of the valve even after the flow passageway is closed by the butterfly disc.